Mobile devices, such as cellular phones, Personal Digital Assistants (PDAs) and portable game consoles continue to grow in popularity. FIG. 1 illustrates an example of such a mobile device. In particular, FIG. 1 illustrates a mobile device 100 connected to a mobile display 102 via an interface 104. The mobile device 100 includes a central processing unit 106 and a graphic controller 108. The mobile display 102 includes a display controller 110 and a display 112, such as a liquid crystal display. A battery 114 powers the mobile device 100 and the mobile display 102. Low power design is critical in mobile applications of this type.
A conventional mobile device interface 104 uses parallel channels with single-ended full-swing signaling. The channels are composed of many lines, for example, 22 lines with 18-bit video pixel data lines and control signal lines, such as dot-clock, data enable (DE), horizontal sync (HSYNC), vertical sync (VSYNC), and other display-specific configuration settings. These signal lines consume power and space. In addition, they produce excessive electromagnetic radiation. To reduce the number of lines, a serial link with low-voltage swing differential signaling may be used. As known in the art, this type of signaling amplifies difference signals, while rejecting common-mode signals.
Popular display interfaces, such as Low Voltage Differential Signaling (LVDS) and Digital Visual Interface (DVI) use 3 channels of serialized differential signals for 18-bit or 24-bit pixel color data. In addition, a separate channel is used for clock transmission. In such an application, the voltage swing is reduced to about 400 mV.
In certain applications, such as a mobile display, relatively low video resolution is acceptable. In such a case, it is possible to use a single data channel. However, in this situation, the prior art has relied upon a separate clock channel. Since the dedicated channel solely for clock transmission increases hardware costs and power, it would be desirable to remove the dedicated clock channel and use only a single channel for transmitting the clock, data and control signals. However, if conventional network protocols, such as 802.3z Gigabit Ethernet are employed, a number of problems arise. For example, a local reference clock must be used at the receiver. This increases hardware costs and reduces flexibility in transmission bandwidth.
In view of the foregoing, it would be desirable to provide a low-power mobile device with a serial channel that supports clock, data and control signals, such as DC balancing control signals.